We aren't spot #5...the numbers are the actual place in the table, so that's Man Utd, heh. We're spot #15: poor defense/ruthless opponents, marginally above-average creativity/attack overall.
We've been xG darlings for some time, but the pattern is consistent enough that it likely has something to do with our ability to generate chances that we don't finish, and the tendency of our defense to melt down spectacularly. Ings has helped on the chance conversion front, but we still fluff our lines to an extent unrivaled in the league. By xG/xGA, the second most "unlucky" (or least composed, depending on how you view it) team is Chelsea, whose goal differential is about 9.1 goals worse than their expected goal differential. Ours is 14.6 goals worse.